The intensive use of antibiotics has exerted a selective evolutionary pressure on microorganisms to produce genetically based resistance mechanisms. Modern medicine and socio-economic behaviour exacerbates the problem of resistance development by creating slow growth situations for pathogenic microbes, e.g. in artificial joints, and by supporting long-term host reservoirs, e.g. in immuno-compromised patients.
In hospital settings, an increasing number of strains of Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus spp., and Pseudomonas aeruginosa, major sources of infections, are becoming multi-drug resistant and therefore difficult if not impossible to treat:                S. aureus is resistant to β-lactams, quinolones and now even to vancomycin;        S. pneumoniae is becoming resistant to penicillin or quinolone antibiotics and even to new macrolides;        Enteroccocci are quinolone and vancomycin resistant and β-lactam antibiotics are inefficacious against these strains;        Enterobacteriacea are cephalosporin and quinolone resistant;        P. aeruginosa are β-lactam and quinolone resistant.        
Furthermore, the incidence of multi-drug-resistant Gram negative strains such as Enterobacteriacea and Pseudomonas aeruginosa, is steadily increasing and new emerging organisms like Acinetobacter spp., which have been selected during therapy with the currently used antibiotics, are becoming a real problem in hospital settings. Therefore, there is a high medical need for new antibacterial agents which overcome multidrug-resistant Gram negative bacilli such as A. baumannii, ESBL-producing E. coli and Klebsiella species and Pseudomonas aeruginosa (Clinical Infectious Diseases (2006), 42657-68).
In addition, microorganisms that are causing persistent infections are increasingly being recognized as causative agents or cofactors of severe chronic diseases like peptic ulcers or heart diseases.
WO 2006/032466 discloses antibacterial compounds that may possess almost all structural motifs of the compounds of the instant invention, except however, on the one hand, the amino group on the ethane-1,2-diyl chain that is located between the quinoline or naphthyridine motif and the tetrahydropyran motif of the molecules and, on the other hand, the hydroxymethyl or alkoxycarbonyl side chain on the quinoline motif when such motif is present.
WO 2006/125974 discloses generically antibacterial compounds that may possess all structural motifs of the compounds of the instant invention. In this document, there is however no concrete example of a compound comprising an amino group on the ethane-1,2-diyl chain that is located between the quinoline or naphthyridine motif and the tetrahydropyran motif of the molecules.
Besides, WO 2006/046552 discloses similar antibacterial compounds that may feature a hydroxymethyl or alkoxycarbonyl side chain on the quinoline motif when such motif is present in the molecules. Unlike the compounds of the instant invention, the antibacterial compounds described in this document do however not comprise a tetrahydropyran motif and their quinoline or naphthyridine motif does not bear a substituted 2-amino-ethyl motif.